Renault's radical exhaust system the Formula One talking point in Valencia

Two years ago it was the hugely controversial ‘double diffuser’, which Brawn
GP exploited brilliantly and which effectively handed Jenson Button his
world title on a platter. To this day it makes Ferrari’s blood boil.

Last year we had the ‘F-duct’, a cunning system which circumvented the ban on moveable parts by making the driver the moveable part, causing him to dance a merry jig down the straights as he closed and opened air vents in the cock-pit. McLaren kept it hidden until the last possible moment and it helped to keep them in the title race until the final day of the season.

Ultimately, they were outdone by Red Bull, who had themselves pioneered the so-called ‘blown floor’, which uses hot exhaust air to improve downforce.

This year Renault’s radical exhaust system, which blows the air out of the leading edge of the sidepods, has everyone at the first pre-season test in Valencia a bit hot under the collar.

Could it be this year’s must-have innovation? Will it carry Renault to an improbable title?

Almost certainly not. They may have pushed the concept further than others but it is unlikely to turn the R31 into a world beater.

Word is a number of other teams are already developing along similar lines, only they haven’t yet incorporated the technology on their cars, either because they do not want anyone copying them or because it is not yet ready.

It would surprise no one if McLaren have something similar to Renault on their MP4-26, which they launch in Berlin on Friday.

The idea behind Renault’s design - which technical director James Allison describes as at “the brave end of brave” - is to channel the hot air under the car as far forward as possible, thereby ensuring that the blown floor works on a greater proportion of the underbody.

Although it did not appear to provide a massive boost to Renault on the first day of pre-season testing on Tuesday, and there are concerns about overheating and controlling exhaust flow, the team are confident the benefits outweigh the risks.

"It's always risky," team principal Eric Boullier said. "But I'm happy that we had some creative designs on the car. We clearly back our team and definitely our technical team because we want to be fast, we want to be at the front.

“You have to find different ways of creating downforce or performance points. We have been taking this path because we believed, quite early in 2010, that we could find more gains going this way.”

The trouble is, everyone else realised that too. Ross Brawn admitted it was a technology that everyone would be harnessing in some form or other.

Asked if his team would be copying Renault, the Mercedes team principal said: “We’ll probably see a number of teams with different solutions before we get to Bahrain.

“I saw Ferrari have some different options. There are a few things you can do to get the benefit from the exhaust energy.”

And that’s the point. Some teams’ solutions may be neater than others but essentially everyone is on to this one. Renault’s system is unlikely to be a game-changer.

You get the feeling we haven’t yet seen the big idea for 2011; the innovation that really causes a stink and has rivals reaching for the rule book. Plenty of time yet.